Quantum-Memory-Enhanced Preparation of Nonlocal Graph States
Abstract
Graph states are an important class of multipartite entangled states. Previous experimental generation of graph states and in particular the Greenberger-Horne-Zeilinger (GHZ) states in linear optics quantum information schemes is subjected to an exponential decay in efficiency versus the system size, which limits its large-scale applications in quantum networks. Here we demonstrate an efficient scheme to prepare graph states with only a polynomial overhead using long-lived atomic quantum memories. We generate atom-photon entangled states in two atomic ensembles asynchronously, retrieve the stored atomic excitations only when both sides succeed, and further project them into a four-photon GHZ state. We measure the fidelity of this GHZ state and further demonstrate its applications in the violation of Bell-type inequalities and in quantum cryptography. Our work demonstrates the prospect of efficient generation of multipartite entangled states in large-scale distributed systems with applications in quantum information processing and metrology.
Cite
@article{arxiv.2202.13386,
title = {Quantum-Memory-Enhanced Preparation of Nonlocal Graph States},
author = {Sheng Zhang and Yu-Kai Wu and Chang Li and Nan Jiang and Yun-Fei Pu and Lu-Ming Duan},
journal= {arXiv preprint arXiv:2202.13386},
year = {2022}
}